UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Income Statement [Abstract]
Oncology services revenue	$ 9,012	$ 6,430	$ 23,375	$ 19,348
Costs and operating expenses:
Cost of oncology services	4,325	3,429	11,958	9,963
Research and development	1,391	1,269	4,035	3,550
Sales and marketing	1,307	879	3,155	2,138
General and administrative	1,556	1,223	4,118	3,311
Total costs and operating expenses	8,579	6,800	23,266	18,962
Income (loss) from operations	433	(370)	109	386
Other income (expense):
Other income (expense)	(14)	1	1	(5)
Income (loss) before provision for income taxes	419	(369)	110	381
Provision for income taxes	12	0	38	0
Net income (loss)	$ 407	$ (369)	$ 72	$ 381
Net income (loss) per common share outstanding
Net income (loss) per common share outstanding, basic (in dollars per share)	$ 0.03	$ (0.03)	$ 0.01	$ 0.03
Net income (loss) per common share outstanding, diluted (in dollars per share)	$ 0.03	$ (0.03)	$ 0.01	$ 0.03
Weighted average common shares outstanding
Weighted average common shares outstanding, basic (in shares)	11,752,619	11,508,180	11,653,115	11,257,314
Weighted average common shares outstanding, diluted (in shares)	13,673,672	11,508,180	13,440,861	13,909,063